The invention in its broad aspects relates to aminoacyl-containing dipeptide derivatives and related compounds which are useful as converting enzyme inhibitors and as antihypertensives. The compounds of this invention are represented by the following formula: ##STR1## wherein
R and R.sub.7 are independently hydrogen, loweralkyl, aryl, aralkyl;
R.sup.1 is hydrogen; alkyl of from 1-12 carbon atoms which include branched and unsaturated groups and cyclic groups of 3-9 carbon atoms; substituted lower alkyl of 2-8 carbon atoms wherein the substituent(s) are halo, hydroxy, carboxy, carboxamido, loweralkylthio, loweralkoxy, loweralkoxycarbonyl, arylthio, aryloxy, aralkylthio, aralkyloxy, amino, loweralkylamino, diloweralkylamino, arylamino, arloweralkylamino, acylamino, acyl loweralkylamino, acyl arylamino, acyl aralkylamino, .dbd.O, .dbd.S or ureido; benzofused cycloalkyl and bicycloalkyl of 8 to 12 carbon atoms which can be substituted by one or more of the foregoing substituents; aryl, arloweralkyl, heteroaryl, heteroarloweralkyl, and those groups substituted by one or more of the foregoing substituents, the aryl or heteroaryl portions thereof being optionally mono-, di- or trisubstituted by halo, loweralkyl, hydroxy, loweralkoxy, amino, aminoloweralkyl, substituted aminoloweralkyl, hydroxyloweralkyl, acylamino, carboxy, halolower alkyl, nitro, cyano or sulfonamido; all of said foregoing substituents containing an aryl or heteroaryl group in which the aromatic rings are partially or completely hydrogenated;
n is 1 to 5;
r is 0 to 3;
R.sub.2 is hydrogen, loweralkyl;
R.sub.3 is hydrogen, aryl, hydroxyaryl, loweralkyl, loweralkyl substituted with aryl, carboxy, heteroaryl, amino, hydroxy, guanidino, alkylthio, mercapto, or alkyloxy;
R.sub.4 and R.sub.5 are independently hydrogen, loweralkyl; or,
R.sub.3 and R.sub.5 can be joined to form a 5- to 6-membered ring having the formula: ##STR2## wherein V is --CH.sub.2 CH.sub.2 --, --CH.sub.2 --, S, --CH(OR.sub.2)-- and wherein R.sub.2 is the same as defined above;
A is loweralkyl, C.sub.3 -C.sub.8 cycloalkyl; C.sub.8 -C.sub.12 bicycloalkyl; benzofused C.sub.3 -C.sub.8 cycloalkyl; perhydrobenzofused C.sub.3 -C.sub.8 cycloalkyl; aryl; aralkyl; heteroaryl; heteroaralkyl; perhydroheteroaryl, or perhydroheteroaralkyl; all of which can be substituted by loweralkyl, loweralkoxy, halo, hydroxy, amino or acylamino;
B is hydrogen or loweralkyl; or, A and B can be joined, together with the N and C atoms to which they are attached to form a ring having the formulae ##STR3## wherein:
X and Y taken together are --CH.sub.2 --CH.sub.2 --, ##STR4## wherein R.sub.6 is hydrogen or loweralkyl;
R.sub.9 is hydrogen; lower alkyl; cycloalkyl; aryl; aralkyl; heteroaryl; heteroaralkyl; loweralkyloxy; loweralkylthio; aryloxy; arylthio; arloweralkyloxy; arloweralkylthio; acyloxy; amino; mono- or disubstituted loweralkylamino and arloweralkylamino; heteroarloweralkylamino; acylamino in which the acyl group can be loweralkanoyl, arloweralkanoyl, aroyl, heteroaroyl, heteroarloweralkanoyl; carbamoyloxy; or, N-substituted carbamoyloxy; the aromatic ring in said foregoing substituents being optionally mono-, di- or trisubstituted by loweralkyl, loweralkoxy, hydroxy, amino, loweralkylthio, halo, lowerhydroxyalkyl, loweraminoalkyl, sulfonamido, cyano, nitro, aryl, aryloxy, arylthio, or aralkyl; the aromatic rings in said groups containing aryl or heteroaryl groups being completely or partially hydrogenated;
R.sub.10 is hydrogen; loweralkyl; aryl; substituted aryl; aralkyl; or, cycloalkyl; or R.sub.9 and R.sub.10 taken together can form a 5 or 6 membered ring which can contain 0, 1 or 2 S or O atoms;
p is 1 to 3;
q is 1 to 3;
W is absent; --CH.sub.2, or ##STR5##
Z is --(CH.sub.2).sub.m -- wherein m is 0 to 2 provided that m is not O when W is absent;
R.sub.8 is hydrogen; loweralkyl; loweralkoxy; hydroxy, halo; loweralkylthio; or, amino; and, the pharmaceutically acceptable salts thereof.
Except where otherwise indicated: the loweralkyl substituents recited above denote straight, branched, saturated or unsaturated hydrocarbon radicals of from one to six carbon atoms such as, for example, methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, n-pentyl, i-pentyl, n-hexyl, vinyl, propargyl, allyl, butenyl, and the like;
loweralkoxy and aryloxy substituents denote loweralkyl and aryl groups attached through an oxygen bridge;
arloweralkyl substituents denote phenyl, naphthyl, or biphenyl attached through a straight or branched chain hydrocarbon of from one to six carbon atoms such as, for example, benzyl;
bicycloalkyl denotes two 5-7 membered cycloalkyl rings fused together such as, for example, perhydroindane, perhydronaphthalene, and the like;
halo denotes chloro, bromo, iodo, or fluoro;
aryl denotes phenyl, naphthyl, or biphenyl;
heteroaryl substituents denote 5- or 6-membered aromatic ring or rings containing 1-3 heteroatoms selected from N, O, and S such as, for example, pyridyl, thienyl, furyl, imidazolyl, thiazolyl, and the like, as well as bicyclic groups in which any of the foregoing heterocyclic rings is fused to another aromatic ring such as, for example, indolyl, quinolinyl, isoquinolinyl, benzimidazolyl, benzothiazolyl, benzothienyl, naphthyridyl, and the like;
substituted aryl denotes aryl rings substituted with hydroxy, loweralkoxy, or halo;
substituted heteroaryl denotes such ring groups substituted with hydroxy, amino, loweralkoxy, or halo;
partially or completely hydrogenated aryl or heteroaryl denote such ring groups in which one or more of the double bonds has (have) been reduced such as, for example, indolinyl, tetralyl, tetrahydroisoquinolyl, piperidinyl, and the like;
acylamino denotes loweralkanoylamino (such as acetylamino), aroylamino (such as benzoylamino), heteroaroylamino (such as thienoylamino), aralkanoylamino (such as phenylbutanoylamino), substituted alkanoylamino and substituted aralkanoylamino in which the substituents are hydroxy, oxo, or amino (such as carbobenzyloxyamino, phenylalanylamino, glycylamino, serylamino, .beta.-alanylamino, and the like).
Preferred are those compounds of Formula I wherein:
R and R.sub.7 are independently hydrogen; loweralkyl; aralkyl;
R.sub.1 is as defined above;
n is 2 to 5;
r is 0;
R.sub.3 is hydrogen, aryl, hydroxyaryl, loweralkyl, loweralkyl substituted with aryl, carboxy, heteroaryl, amino, hydroxy, guanidino, or alkylthio groups;
R.sub.3 and R.sub.5 can be joined to form a 5- to 6-membered ring having the forumla: ##STR6## wherein V is --CH.sub.2, S, --CH--OR.sub.2 --;
R.sub.4 is hydrogen;
A is cycloalkyl containing 3-8 carbons in the ring, C.sub.9-10 bicycloalkyl, benzofused cycloalkyl, or perhydrobenzofused cycloalkyl;
B is hydrogen or A and B can be joined together to form a ring in which
p is 1;
q is 1-2; and,
X and Y taken together are --CH.sub.2 CH.sub.2 --, CHR.sub.6 S, COCH.sub.2, CH.sub.2 CHR.sub.9, CH.sub.2 CO, CH.sub.2 CHOR.sub.9, wherein R.sub.6 is hydrogen and R.sub.9 is hydrogen, loweralkyl, aryl, or cycloalkyl, or
X and Y taken together with the N and C atoms to which they are attached are joined to form a ring having the formulae: ##STR7##
Still more preferred are those compounds of Formula I wherein:
R and R.sub.7 are independently hydrogen, loweralkyl, benzyl;
R.sub.1 is alkyl having from 1 to 8 carbon atoms; substituted lower alkyl wherein the alkyl group has 1-5 carbon atoms and the substituent is amino, arylamino, acylarylamino, arylthio, aryloxy or arylamino; aralkyl or heteroaralkyl wherein the alkyl portion has 1 to 3 carbon atoms (such as phenethyl or imidazolylethyl) or substituted arloweralkyl and substituted heteroarlower-alkyl wherein the alkyl groups have 1-3 carbons and wherein the substituent(s) is (are) halo, nitro, cyano, sulfonamido, amino, aminoalkyl, hydroxyalkyl, hydroxy, lower alkoxy or lower alkyl and on the alkyl group the substituents are optionally amino, acylamino and hydroxy;
n is 2 to 4;
r is 0;
R.sub.3 is hydrogen, aryl, hydroxyaryl, loweralkyl, loweralkyl substituted with aryl, carboxy, heteroaryl, amino, hydroxy, guanidino, or alkylthio groups,
R.sub.2, R.sub.4 and R.sub.5 are hydrogen;
A is cyclopentyl or indanyl;
B is hydrogen; and,
p is 1;
q is 1-2; and,
X and Y taken together are --CH.sub.2 CH.sub.2 --, CHR.sub.6 S, CH.sub.2 CHR.sub.9, COCH.sub.2, CH.sub.2 CHOR.sub.9 wherein R.sub.6 is hydrogen and R.sub.9 is aryl or cycloalkyl; or
X and Y taken together with the N and C atoms to which they are attached are joined to form a ring having the formulae: ##STR8##
Most preferred are compounds of Formula I wherein:
R and R.sub.7 are independently hydrogen, loweralkyl, benzyl;
R.sub.1 is alkyl having from 1 to 8 carbon atoms; substituted lower alkyl wherein the alkyl group has 1-5 carbon atoms and the substituent is amino, aroylamino, aroylarylamino, aroylaralkylamino, arylthio or aryloxy; aralkyl or heteroaralkyl wherein the alkyl portion has 1 to 3 carbon atoms (such as phenethyl or imidazolylethyl) or substituted aralkyl and substituted heteroaralkyl wherein the alkyl groups have 1-3 carbons and wherein the substituent(s) is (are) amino, hydroxy, aroylamino or heteroaroylamino and the aryl and heteroaryl substituents are hydroxy, amino, aminomethyl, nitro, cyano, halo, or sulfonamido;
n is 2 to 4;
r is 0;
R.sub.2 is hydrogen;
R.sub.3 is hydrogen, loweralkyl, loweralkyl substituted with aryl, carboxy, heteroaryl, guanidino, amino, or hydroxy;
R.sub.3 and R.sub.5 can be joined to form a pyrrolidine ring;
R.sub.4 is hydrogen;
A is cyclopentyl or indanyl;
B is hydrogen, or
p is 1;
q is 1-2; and,
X and Y taken together are CH.sub.2 CH.sub.2, CH.sub.2 S, CH.sub.2 CHOH, CH.sub.2 CHR.sub.9 wherein R.sub.9 is cyclohexyl or phenyl, or X and Y taken together with the N and C atoms to which they are joined form a ring having the formulae: ##STR9##
The preferred, more preferred and most preferred compounds also include the pharmaceutically acceptable salts thereof.
The products of Formula (I) can be produced by the methods depicted in the following Reaction Schemes wherein R, R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7, R.sub.8, r.sub.9, n, p, q, r, A, B, U, V, W, X, Y and Z are as defined above. Reactive functionality in these groups is protected as needed with suitable protecting groups as is well known to those skilled in peptide chemistry.
In general, the compounds of this invention can be prepared by reacting a compound having the formula: ##STR10## wherein R, R.sub.1, R.sub.2, R.sub.7, A, B and n are as defined above, with a carboxy activated derivative of a compound having the formula: ##STR11## wherein R.sub.3 and R.sub.4 are as defined above and Q is a suitable protecting group such as t-butoxycarbonyl, benzyloxycarbonyl, and like groups. Activation of the carboxy derivative III is typically accomplished with N-hydroxysuccinimide or N-hydroxybenzotriazole esters. Subsequent removal of the Q protecting group using standard conditions yield compounds of Formula I.
Amino acid derivative III can also be coupled to dipeptide derivative II using dicyclohexylcarbodiimide or diphenylphosphorylazide providing neither R nor R.sub.7 are hydrogen. When either R or R.sub.7 are hydrogen in products of Formula I, the carboxyls in intermediate compounds II should be protected as removable esters such as, for example, with R and/or R.sub.7 benzyl or t-butyl groups.
In the above-described synthesis, only slightly more than one equivalent of activated amino acid derivative III is used to minimize reaction with the NH of intermediate II to which R.sub.1 CHCO.sub.2 R is attached. Alternatively, this NH can be protected during this step with a removable group such as, for example, a formyl function.
Additionally, compounds of Formula I can be synthesized in a step-wise manner as illustrated in the following Reaction Schemes. ##STR12##
In Reaction Scheme I, Z and Q are suitable removable nitrogen protecting groups such as t-butoxycarbonyl or benzyloxycarbonyl functions and R.sub.10 is a removable carboxyl protecting group such as benzyl or t-butyl. The addition and removal of these protecting groups is achieved under standard conditions. Similarly, the peptide coupling reactions of intermediates III with IV and V with VI are conducted with coupling reagents standard in peptide chemistry, some of which are noted above while others are illustrated in the Examples set forth hereinbelow.
The reductive coupling of R.sub.1 COCO.sub.2 R to intermediate VII (Z=H) is achieved by the use of sodium cyanoborohydride or with hydrogen in the presence of catalysts such as palladium or Raney nickel.
In Reaction Scheme II, dipeptide VIII results from the coupling of intermediates IX and VI in which protecting group J is subsequently removed in the presence of protecting group Z. Intermediate III is then coupled to intermediate VIII in the same manner as described for the synthesis of V from the coupling of III with IV in Reaction Scheme I.
Reaction Scheme III illustrates a further synthetic variant wherein the order of the coupling reactions is changed so that properly protected XI is coupled to intermediate VI to yield products of Formula I. In this coupling reaction, neither R nor Q is hydrogen, but either may subsequently be converted to hydrogen by standard methods, if this is desired.
Formula I compounds wherein R.sub.2 =loweralkyl can be prepared by reacting intermediates II, IV and VIII (R.sub.2 =H) with aldehydes (1 molar equivalent) in the presence of NaCNBH.sub.3, or stepwise by first forming the N-benzyl derivative using 1 equivalent of benzaldehyde and NaCNBH.sub.3, followed by treatment with formaldehyde or loweralkylaldehyde with NaCNBH.sub.3, and finally removing the benzyl protecting groups by hydrogenolysis using Pd/C catalyst.
The above described syntheses can utilize racemates, enantiomers or diastereomers as starting materials or as intermediates. When diastereomeric products result from the synthetic procedures, the diastereomeric products can be separated by conventional chromatographic or fractional crystallization methods.
In products of general Formula I, the carbon atoms to which the group, (CH.sub.2).sub.n NR.sub.2 COCR.sub.3 R.sub.4 (CH.sub.2).sub.r NR.sub.5 H, is attached is asymmetric as are the carbons to which R.sub.1, R.sub.3, R.sub.4 and B are attached when these groups are not hydrogen. In general, L-amino acid configurations are preferred throughout. However, at the carbons to which R.sub.3, R.sub.4 and B are attached, D-amino acid configurations are sometimes consistent with good activity and confer additional metabolic stability. In most instances, L-amino acid configurations can be alternatively designated as (S)- and D-amino acid configurations as (R)-configurations.
The compounds of this invention form salts with various inorganic and organic acids and bases which are also within the scope of the invention. Such salts include ammonium salts, alkali metal salts like sodium and potassium salts, alkaline earth metal salts like the calcium and magnesium salts, salts with organic bases e.g., dicyclohexylamine salts, N-methyl-D-glucamine, salts with amino acids like arginine, lysine and the like. Also salts with organic and inorganic acids may be prepared, e.g., HCl, HBr, H.sub.2 SO.sub.4, H.sub.3 PO.sub.4, methanesulfonic, toluensulfonic, maleic, fumaric, camphorsulfonic acid. The non-toxic physiologically acceptable salts are preferred, although other salts are also useful, e.g., in isolating or purifying the product.
The salts may be formed by conventional means as by reacting the free acid or free base forms of the product with one or more equivalents of the appropriate base or acid in a solvent or medium in which the salt is insoluble, or in a solvent such as water which is then removed in vacuo or by freeze-drying or by exchanging the cations of an existing salt for another cation on a suitable ion exchange resin.
The compounds of this invention inhibit angiotensin converting enzyme and thus block conversion of the decapeptide angiotensin I to angiotensin II. Angiotensin II is a potent pressor substance. Thus, blood-pressure lowering can result from inhibition of its biosynthesis especially in animals and humans whose hypertension is angiotensin II related. Furthermore, converting enzyme degrades the vasodepressor substance, bradykinin. Therefore, inhibitors of angiotensin converting enzyme may lower blood-pressure also by potentiation of bradykinin. Although the relative importance of these and other possible mechanisms remains to be established, inhibitors of angiotensin converting enzyme are effective antihypertensive agents in a variety of animal models and are useful clinically, for example, in many human patients with renovascular, malignant and essential hypertension and in the treatment of congestive heart failure. See, for example, D. W. Cushman et al., Biochemistry 16, 5484 (1977).
The evaluation of converting enzyme inhibitors is guided by in vitro enzyme inhibition assays. For example, a useful method is that of Y. Piquilloud, A. Reinharz and M. Roth, Biochem. Biophys. Acta, 206, 136 (1970) in which the hydrolysis of carbobenzyloxyphenylalanylhistidinylleucine is measured. In vivo evaluations may be made, for example, in normotensive rats challenged with angiotensin I by the technique of J. R. Weeks and J. A. Jones, Proc. Soc. Exp. Biol. Med., 104, 646 (1960) or in a high renin rat model such as that of S. Koletsky et al., Proc. Soc. Exp. Biol. Med. 125, 96 (1967).
Thus, the compounds of this invention are useful as antihypertensives in treating hypertensive mammals, including humans, and they can be utilized to achieve the reduction of blood pressure by formulating in compositions such as tablets, capsules or elixirs for oral administration or in sterile solutions or suspensions for parenteral administration. The compounds of this invention can be administered to patients in need of such treatment in a dosage range of 0.5 to 100 mg per patient generally given several times, thus giving a total daily dose of from 0.5 to 400 mg per day. The dose will vary depending on severity of disease, weight of patient and other factors which a person skilled in the art will recognize.
It is often advantageous to administer compounds of this invention in combination with other antihypertensives and/or diuretics. For example, the compounds of this invention can be given in combination with such compounds as amiloride, atenolol, bendroflumethiazide, chlorothalidone, chlorothiazide, clonidine, cryptenamine acetate and cryptenamine tannates, deserpidine, diazoxide, ethacrynic acid, furosemide, guanethidene sulfate, hydralazine hydrochloride, hydrochlorothiazide, hydroflumethiazide, metolazone, metoprolol tartate, methyclothiazide, methyldopa, methyldopate hydrochloride, minoxidil, (S)-1-{[2-(3,4-dimethoxyphenyl)ethyl]amino}-3-{[4-(2-thienyl)-1H-imidazol- 2-yl]phenoxy}-2-propanol, polythiazide, the pivaloyloxyethyl ester of methyldopa, indacrinone and variable ratios of its enantiomers, nifedipine, verapamil, diltiazam, flumethiazide, bendroflumethiazide, atenolol, (+)-4-{ 3-}-[2-(1-hydroxy-cyclohexyl)ethyl]-4-oxo-2-thiazolidinyl}propyl}benzoic acid, bumetanide, prazosin, propranolol, rauwolfia serpentina, rescinnamine, reserpine, spironolactone, timolol, trichlormethiazide, benzthiazide, quinethazone, tricrynafan, triamterene, acetazolamide, aminophylline, cyclothiazide, merethoxylline procaine, and the like, as well as admixtures and combinations thereof.
Typically, the individual daily dosages for these combinations can range from about one-fifth of the minimally recommended clinical dosages to the maximum recommended levels for the entities when they are given singly.
To illustrate these combinations, one of the antihypertensives of this invention effective clinically in the 2.5-100 milligrams per day range can be effectively combined at levels at the 0.5-100 milligrams per day range with the following comounds at the indicated per day dose range: hydrochlorothiazide (10-100 mg), timolol (5-60) mg), methyl dopa (65-2000 mg), the pivaloyloxyethyl ester of methyl dopa (30-1000 mg), indacrinone and variable ratios of its enantiomers (25-150 mg) and (+)-4- {3-{[2-(1-hydroxycyclohexyl)ethyl]-4-oxo-2-thiazolidinyl}propyl}-benzoic acid (10-100 mg).
In addition, the triple drug combinations of hydrochlorothiazide (10-100 mg) plus timolol (5-60 mg) plus converting enzyme inhibitor of this invention (0.5-100 mg) or hydrochlorothiazide (10-100 mg) plus amiloride (5-20 mg) plus converting enzyme inhibitor of this invention (0.5-100 mg) are effective combinations to control blood pressure in hypertensive patients. Naturally, these dose ranges can be adjusted on a unit basis as necessary to permit divided daily dosage and, as noted above, the dose will vary depending on the nature and severity of the disease, weight of patient, special diets and other factors.
Typically, the combinations shown above are formulated into pharmaceutical compositions as discussed below.
About 0.5 to 100 mg of a compound or mixture of compounds of Formula I or a physiologically acceptable salt is compounded with a physiologically acceptable vehicle, carrier, excipient, binder, preservative, stabilizer, flavor, etc., in a unit dosage form as called for by accepted pharmaceutical practice. The amount of active substance in these compositions or preparations is such that a suitable dosage in the range indicated is obtained.
Illustrative of the adjuvants which may be incorporated in tablets, capsules and the like are the following: a binder such as gum tragacanth, acacia, corn starch or gelatin; an excipient such as microcrystalline cellulose; a disintegrating agent such as corn starch, pregelatinized starch, alginic acid and the like; a lubricant such as magnesium stearate; a sweetening agent such as sucrose, lactose or saccharin; a flavoring agent such as peppermint, oil of wintergreen or cherry. When the dosage unit form is a capsule, it may contain, in addition to materials of the above type, a liquid carrier such as fatty oil. Various other materials may be present as coatings or to otherwise modify the physical form of the dosage unit. For instance, tablets may be coated with shellac, sugar or both. A syrup or elixir may contain the active compound, sucrose as a sweetening agent, methyl and propyl parabens as preservatives, a dye and a flavoring such as cherry or orange flavor.
Sterile compositions for injection can be formulated according to conventional pharmaceutical practice by dissolving or suspending the active substance in a vehicle such as water for injection, a naturally occurring vegetable oil like sesame oil, coconut oil, peanut oil, cottonseed oil, etc. or a synthetic fatty vehicle like ethyl oleate or the like. Buffers, preservatives, antioxidants and the like can be incorporated as required.